Which is the problem my monitor or windows?

I have a weird problem in games the resolutions do not work well, my monitor is 1280x1024, the problem is that I resolve it 1360x768 and 1368x768 looks like 720p a little blurry, and the resolution 1440x900 looks like 1280x1024, someone You know why that is, the graphics card is not the problem since I changed it and it's still the same.

Which is the problem my monitor or windows?
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